Spreadsheet::ParseExcel::Stream doesn't keep the entire spreadsheet in memory at once. Instead, it reads the spreadsheet row-by-row. So to use it, you have to arrange your logic where you don't dare about any data but the current row. Then, as you call each row, use all the data you need, then proceed to the next row.

# Don't do this!
my @defeat_stream;
my $xls = Spreadsheet::ParseExcel::Stream->new($xls_file, \%options);
while ( my $sheet = $xls->sheet() ) {
while ( my $row = $sheet->row ) {
# current row now in memory.
my @data = @$row;
# after this, current row will *disappear*, unless...
# you keep the data.
push @defeat_stream, $row;
}
}
# Now you either have the entire spreadsheet in memory (defeating the +purpose
# of the module), or have run out of memory.

Note: Don't keep all the data around for future use, as I do above, as then you're throwing away the advantage of the module. But since you don't read everything into RAM at once, you could extract what you need, and then iterate over it.